Answer
Block 1 is stationary after the collision.
Work Step by Step
If the center of mass is at point B, then $m_1 = m_2$
We can use equation (9-67) to find an expression for the final velocity $v_{1f}$ of block 1 after the collision:
$v_{1f} = \frac{m_1-m_2}{m_1+m_2}~v_{1i}$
Since $m_1 = m_2,$ then $v_{1f} = 0,$ so block 1 is stationary after the collision.
